December 17, 2008
A popular drug used to treat the seizures of epilepsy showed early promise in the treatment of Alzheimer's disease, researchers say. The drug, valproic acid, showed benefits for the brains of mice that had been specially bred to develop an illness than resembles Alzheimer's in people.
It's a long way from rodents to humans, and the vast majority of drugs that show early promise in animals never make it to late-stage testing in humans. However valproic acid is currently being tested in people with Alzheimer's In the mouse tests, mice given valproic acid had less accumulation of beta-amyloid deposits, or plaque, in the brain.
Mice with early signs of Alzheimer's that were given the drug also performed better on memory tests, like guiding their way through mazes. The drug produced greater benefit when treatment was started early (in young mice) , compared to treatment that started later (in old mice). The findings appeared in the online version of The Journal of Experimental Medicine.
The researchers, from the University of British Columbia in Vancouver, didn't test valproic acid in people. They speculate, however, that valproic acid might benefit people with early or mild Alzheimer's disease.
Valproic acid is commonly sold as Depakene, Depakote or Valproate in the United States, and as Convulex in Britain. In addition to epilepsy, it is also sometime prescribed to treat bipolar disorder and schizophrenia.
Various studies of valproic acid and Alzheimer's disease in humans are currently under way. One, called the VALID trial, for Valproate in Dementia, is looking at whether the drug delays the onset of agitation and psychosis in people with dementia who have not had these behavioral problems. Aggression and agitation are common as Alzheimer's progresses. Researchers will also be studying whether the drug delays memory and thinking problems in people with early Alzheimer's.
Valproic acid seems to work by blocking a cascade of chemical reactions in the brain that culminates in the accumulation of beta-amyloid, a protein that builds up to toxic levels in Alzheimer's disease. The drug is generally safe, though like all drugs, may have side effects. More testing is needed to determine if it is effective in easing the cognitive decline or behavioral problems of Alzheimer's disease.
Qing, H. The Journal of Experimental Medicine, Oct. 27, 2008; advance online edition.